Abstract. — The Atlantic spa- 

 defish (Chaetodipterus faber) is the 

 only member of the family 

 Ephippidae in the western Atlan- 

 tic Ocean and its life history is 

 poorly understood. We redescribe 

 Atlantic spadefish larvae, discuss 

 their relationship to known larvae 

 of other ephippid genera, and dis- 

 cuss the distribution, abundance, 

 and seasonal occurrence of Atlan- 

 tic spadefish in the northern Gulf 

 of Mexico. Larval Atlantic spade- 

 fish are characterized by a small, 

 peak-like, median supraoccipital 

 crest with a single, dorsally di- 

 rected spine; large preopercle 

 spines, numerous serrate ridges, 

 and other spines on the head; a 

 deep, robust body which becomes 

 laterally compressed; heavy body 

 pigmentation; and early develop- 

 ment of specialized spinous scales 

 or "prescales" (at about 5.5-mm 

 standard length [SL]). Transition 

 to juvenile stage begins about 8.0- 

 8.5 mm SL. Developmental mor- 

 phology and head spination of At- 

 lantic spadefish is similar to that 

 of Pacific spadefish, Chaetodipter- 

 us zonatus. Sequence of fin com- 

 pletion is pelvics — dorsal and 

 anal soft rays — dorsal spines- 

 pectorals. Overall, >85% of Atlan- 

 tic spadefish larvae were found in 

 waters >28.0°C and between 26.7 

 and 31.3 ppt. Larvae occur prima- 

 rily in coastal waters, except near 

 the Mississippi River delta, an 

 area with a narrow shelf and rap- 

 idly increasing water depths. 

 Delta waters may offer additional 

 habitat suitable to Atlantic spade- 

 fish larvae because of lower salini- 

 ties. Larvae are primarily collected 

 between June and August and in 

 the north-central Gulf of Mexico. 

 Larval Atlantic spadefish are ap- 

 parently rare in the eastern Gulf 

 off Florida. Catch rates near the 

 Mississippi River delta during 

 August were higher than else- 

 where in the north-central Gulf 

 and suggest a possible association 

 with riverine frontal areas which 

 requires further study. 



A re-description of Atlantic spadefish 

 larvae, Chaetodipterus faber (family: 

 Ephippidae), and their distribution, 

 abundance, and seasonal occurrence 

 in the northern Gulf of Mexico 



James G. Ditty 

 Richard F. Shaw 

 Joseph S. Cope 



Coastal Fisheries Institute, Center for Coastal, Energy, and Environmental Resources 

 Louisiana State University, Baton Rouge, LA 70803 



The percoid family Ephippidae is 

 usually considered to comprise five 

 genera and 17 species (Nelson, 

 1984). The Atlantic spadefish (Chae- 

 todipterus faber) is the only mem- 

 ber of this family in the western 

 Atlantic Ocean. Rare north of 

 Chesapeake Bay, Atlantic spadefish 

 inhabit coastal waters which ex- 

 tend southward to Brazil (Johnson, 

 1978). Historically, Atlantic spade- 

 fish represented a relatively minor 

 portion of recreational fisheries. 

 Nevertheless, fishing tournaments 

 are currently being used to stimu- 

 late interest in their fisheries 

 (Schmied and Burgess, 1987). 

 Ryder (1887) described eggs and 

 yolk-sac larvae of Atlantic spade- 

 fish, but Johnson (1978) questioned 

 the identity of these specimens. 

 Larvae >2.5 mm standard length 

 (SL) are described and illustrated 

 by Hildebrand and Cable (1938), 

 but this study is insufficient to ex- 

 amine important developmental 

 details and is based on the static 

 rather than dynamic approach to 

 larval description (Berry and 

 Richards, 1973). Finucane et al. 1 

 illustrated 5.1- and 6.4-mm SL At- 

 lantic spadefish. Johnson (1984) 

 commented on cranial morphology 



and provided insight on the value 

 of larval characters in resolving the 

 relations among ephippids and 

 their relation to other families. 

 Aspects of juvenile and adult life 

 history are discussed for Atlantic 

 spadefish from South Carolina wa- 

 ters (Hayse, 1990), but the distri- 

 bution, abundance, and seasonal 

 occurrence of Atlantic spadefish 

 larvae are poorly understood. Our 

 objectives are to redescribe the de- 

 velopment of Atlantic spadefish lar- 

 vae, discuss their relation to known 

 larvae of other ephippid genera, 

 and to describe the distribution, 

 abundance, and seasonal occurrence 

 of Atlantic spadefish larvae in the 

 northern Gulf of Mexico (Gulf). 



Materials and methods 



The distribution, abundance, and 

 seasonal occurrence of larval Atian- 



Finucane. J. H., L. A. Collins, L. E. 

 Barger, and J. D. McEachran. 1979. 

 Ichthyoplankton/mackerel eggs and lar- 

 vae. Environmental studies of the south 

 Texas outer continental shelf, 1977. Final 

 Rep. to Bur. Land Manage., Wash., DC, 

 Southeast Fish. Cent., Natl. Mar. Fish. 

 Serv. NOAA, Galveston, TX 77550, 504 p. 



Manuscript accepted 19 August 1993 

 Fishery Bulletin 92:262-274 (1994) 



Contribution No. LSU-CFI-92-7 of Louisiana State University Coastal Fisheries 

 Institute. 



262 



